JP2007281145A - Flexible wiring member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible wiring member scarcely subjected to a tensile stress upon the bending thereof and wherein the disconnection of a shield wiring pattern scarcely occurs, and comprising a shield structure wherein the shielding ability and flexibility thereof are compatible. <P>SOLUTION: This long tabular flexible wiring member 100 has a line pattern LP1 and a shield pattern SP1 wired thereon. The flexible wiring member 100 has a bending portion B1 at the position intersecting the wiring direction of the line pattern LP1, and the bending portion B1 has bending lines BS1 orthogonal to the bending direction. The shield pattern SP1 includes wiring parallel to the bending lines BS1 in the bending portion B1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a flexible printed circuit board (FPC: Flexible Printed Circuits) having a wiring pattern for shielding as an electromagnetic wave shielding layer, a flexible flat cable (FFC), and the like. The present invention relates to a flexible wiring body that can prevent bending of a shield pattern wiring due to bending stress or sliding to improve bending strength and flexibility.

  In recent years, electronic devices such as mobile phones, personal computers, cameras, and radio cassettes have been increasingly shifted to smaller, lighter, and thinner devices due to user demands. For this reason, the printed wiring boards and cables used in these devices are also small, lightweight and thin flexible printed wiring boards (FPC) and flexible flat cables (FFC).

  Wiring bodies such as flexible printed wiring boards and flexible flat cables used in these devices must be shielded against external and internal noise. This is because if the shielding is not performed, the signal is affected by noise, the original power transmission characteristics are deteriorated, and the product may be damaged.

  FIG. 6 is an explanatory view showing a structural example of a conventional flexible printed wiring board (FPC) in an external perspective view. The FPC 600 here includes a base substrate 61 in which materials such as silica, paper, lacquer, glue, and other animal and plant fibers, biodegradable plastics, flame retardant polyolefin, and polyester are formed in a thin plate shape. Is provided with a first metal layer 62. The metal layer 62 is a conductor pattern layer 62 in which a conductor pattern (signal pattern) formed using a printing technique or the like is formed. The conductor pattern layer 62 is coated with an insulating coating layer (coverlay) 63 such as polyimide / polyester, and a second metal layer 64 is provided on the insulating coating layer 63.

  The second metal layer 64 is an electromagnetic wave shielding layer that shields noise from the outside, that is, a shield layer 64. For example, a copper / silver or carbon conductive paste (electromagnetic wave shielding layer) is applied to a solid using a printing technique. After coating or mesh printing, it can be formed by heat curing. Further, in order to protect the shield layer 64, a protective layer 65 (coverlay) made of polyimide, polyester or the like is provided thereon.

In the technical field related to the flexible wiring body including the shield layer as in the present invention, for example, the following patent documents are known.
JP 2003-168862 A JP-A-2005-251958

Here, an example of a shield structure of a flexible printed wiring board (FPC) conventionally used will be specifically described with reference to FIGS.
FIG. 3 shows a first example of the shield structure of the FPC, and the FPC 300 is a long flat plate-like flexible cable having a wiring line (line pattern) LP3 inside, and its central portion is slightly constricted. A shielding sheet ST3 such as an aluminum vapor deposited sheet or a copper foil sheet is wound around the line pattern, thereby forming a shield layer.

FIG. 4 shows a second example of the shield structure of the FPC. The FPC 400 has a long plate-like flexible wiring in which a line pattern LP4 is provided on the front side and a shield pattern SP4 is provided on the back side. The shield pattern SP4 here is a shield pattern having a solid ground structure.
FIG. 5 shows a third example of the shield structure of the FPC. The FPC 500 has a long plate-like flexible structure in which a line pattern LP5 is provided on the front side and a shield pattern SP5 is provided on the back side. It is a cable body, Comprising: The shield pattern SP5 here is a shield pattern by a mesh structure.

Next, problems of the shield structure in the conventional FPC will be described.
In the FPC 300 of FIG. 3, a shielding sheet ST1 such as an aluminum vapor-deposited sheet or a copper foil sheet to be wound around the wiring line is separately required, so that the number of parts increases and the cost of the mounting work increases. Up is a problem.
Further, in the FPC 400 of FIG. 4 and the FPC 500 of FIG. 5, a shield line pattern having a tagurant structure or a mesh structure is provided on the back surface of the FPC wiring line (line pattern). It is composed of copper foil and through-hole plating (copper plating). The greater the number of lines and the thicker the line, the more rigid the FPC will be. ) Performance cannot be demonstrated.

  In a flexible cable having a shield pattern having a tagrant structure or a mesh structure such as FPC 400 and FPC 500, a wiring pattern in which the shield pattern is parallel or intersects with respect to the bending direction when bending the cable. Therefore, when bending the FPC, a large force is generated in a direction in which the FPC is pulled (or contracted), and thus there is a problem that the pattern is likely to be disconnected.

  The FPC 400 in FIG. 4 will be described in more detail. The FPC 400 is a long flat plate-shaped flexible cable body including a main part A4-intermediate part B4-main part C4, and the intermediate part B4 is a bent part. When stress is applied in the bending directions (D4 and D4 ′), the bending portion B4 is bent, and a large number of bending lines BS4 are generated in the bending portion B4. The bending lines BS4 are bent in the bending direction (D4-D4). It is a line perpendicular to ') or intersected with an angle. The shield pattern SP4 of the FPC 400 becomes the outer side when bent, and has a larger radius of curvature than the line pattern LP4 on the inner side, so that a greater tensile stress is applied and the shield pattern is likely to break. It has become.

  The present invention has been made in view of the above-mentioned problems, and does not require a shield sheet made of a separate part such as an aluminum vapor-deposited sheet or a copper foil sheet. Flexible wiring comprising a shield structure that can achieve both shielding properties and flexibility without easily breaking the sealed pattern even when stresses associated with operations such as bending, twisting, pulling, and sliding are applied The purpose is to provide a body.

(1) In a long flat flexible wiring body in which a line pattern and a shield pattern are wired together,
The flexible wiring body has a bent portion at a position intersecting the wiring direction of the line pattern,
The folding portion has a folding line orthogonal to the folding direction;
The shield pattern includes a wiring parallel to the fold line at the fold portion.

(2) In the flexible wiring body of (1),
The shield pattern includes a wiring parallel to the fold line and a wiring intersecting with the fold line in the bent portion.
(3) In the flexible wiring body of (2),
The shield pattern is configured in a ladder pattern by a plurality of wirings parallel to the folding line and at least two wirings orthogonal to the folding line.
(4) In the flexible wiring body of (1),
The shield pattern includes a wiring pattern in the bent portion, and a wiring pattern other than the bent portion,
The wiring pattern other than the bent portion is constituted by a mesh pattern or a solid ground pattern.

  In the flexible wiring body according to the present invention, there is a bent portion at a position intersecting with the wiring direction of the line pattern, the bent portion has a folding line orthogonal to the bending direction, and the shield pattern has the bending line at the bent portion. It is configured with parallel wiring. Therefore, the wiring parallel to the fold line of the shield pattern is not subjected to tensile stress even when bent, and the flexible wiring body itself does not become hard when bent, and the shield pattern is less likely to break. Therefore, it is possible to provide a flexible wiring body having a shield structure capable of satisfying both properties and flexibility.

Now, an embodiment of the flexible wiring body according to the present invention will be described with reference to FIG. 1 (first embodiment) and FIG. 2 (second embodiment).
FIG. 1 (1) shows an FPC 100, which is a long flat-plate-shaped flexible cable body composed of a main part A1-intermediate part B1 (bent part) -main part C1, in a front / side / back (back) side. It is the external view seen from the direction. In the FPC 100, a line pattern LP1 is wired along the longitudinal direction on one surface side (front surface side), and a main part A1 (upper part) and a main part C1 (lower part) are connected via an intermediate part B1. Electrically connected. Further, a shield pattern SP1 is wired alongside the line pattern LP1 on the other surface side (back surface side), and the main part A1 (upper part) and the main part C1 ((lower part) pass through the intermediate part B1. Are electrically connected.

  FIG. 1 (2) is an explanatory view showing a state when the FPC 100 of FIG. 1 (1) is bent by applying stress in the bending direction (D1 and D1 '). The FPC 100 in FIG. 1 (1) is bent at the bent portion B1, but many bent lines BS1 are generated in the bent portion B1, and are these bent lines BS1 orthogonal to the bending direction (D1-D1 ′)? It becomes a line that intersects it with an angle. When the shield pattern SP1 of the FPC 100 is bent as shown in FIG. 1 (1), the shield pattern SP1 is located outside the bent portion B1 and has a larger radius of curvature than the line pattern LP1 on the inside. The structure is subject to large tensile stress.

  In FIG. 1A, the wiring structure of the shield pattern SP1 of the FPC 100 includes a large number of horizontal wirings (y1 to y12) parallel to a large number of bending lines BS1 in the bent portion B1, and two vertical wirings (x1) at both ends orthogonal to each other. , X2), and as a whole has a “ladder shape”. The vertical wirings (x1, x2) here are ground lines (shield lines) arranged substantially parallel to the bending direction (D1 and D1 ′) of the FPC 100, and the horizontal wirings (y1 to y12) are vertical wirings ( x1 and x2) are ground lines (shield lines) that are arranged substantially perpendicular to the bending direction (D1 and D1 ′) of the FPC 100.

  The wiring of the shield pattern SP1 of the FPC 100 in FIG. 1 (1) has a bent portion B1 at a position intersecting with the wiring direction of the line pattern, and the bent portion B1 has a bent line BS1 orthogonal to the bent direction. The pattern SP1 is configured to include a large number of wirings (lateral wirings: y1 to y12) parallel to the bending line at the bent portion B1. Therefore, the horizontal wirings (y1 to y12) of the shield pattern SP1 are not subjected to stress in the pulling direction even when bent, and the disconnection of the shield pattern SP1 hardly occurs. Moreover, the flexible wiring body (FPC 100) itself does not become hard when bent, and the flexible wiring body 100 having a shield structure that can achieve both shielding properties and flexibility can be obtained.

  Next, FIG. 2 is an external view of the FPC 200 having a shield structure different from that of the FPC 100 as viewed from the direction of the back surface (back surface, shield pattern side). The FPC 200 here is a long flat plate-shaped flexible cable body composed of a main part A2-intermediate part B2 (folded part) -main part C2, but is the same as the FPC 100, but the back side of the FPC 200 The other shield pattern SP2 is wired, and the main part A2 (upper part) and the main part C2 ((lower part)) are electrically connected via the intermediate part B2 (bending part).

  In FIG. 2, the wiring of the shield pattern SP2 in the bent portion B2 of the FPC 200 has a structure “P1 + P2 + P3” in which patterns P1, P2, and P3 are integrally combined in a flat plate shape. The patterns P1 and P3 are A shield pattern having the same mesh structure is used, and a pattern P2 having a ladder-like shield structure similar to the shield pattern SP1 in FIG. 1 is used.

  The pattern P2 at the center of the bent part B2 is composed of a plurality of horizontal wirings (y22, y22) parallel to the bending line BS2, and two vertical wirings (x21, x22) at both ends orthogonal to the pattern P2. The overall structure is a low “ladder” shield structure. Further, in this FPC 200, patterns (P1 and P3) having a conventional shield structure are connected and combined in a planar manner on both ends (upper and lower parts) of the pattern P2, and the bent portion B2 is substantially bent. When it is not necessary to secure a large area as a location, only the location of the pattern P2 can be formed in a “ladder-like” shield structure. Here, a shield pattern having a mesh structure is employed, but a shield pattern having a solid ground structure may be used.

  So far, examples of applying the flexible wiring body according to the present invention to flexible printed circuit boards (FPC) have been mainly described. However, other flexible wiring bodies such as a flexible flat cable (FFC: Flexible Flat Cable) are described. (Cable) is also applicable.

  FIG. 7 is an explanatory view showing a structural example of a flexible flat cable (FFC) by an external perspective view. In this FFC 700, the conductor pattern 71 is coated with an insulating film layer 72 so as to form a flat cable, and then only the insulating film layer 72 in the portion of the ground line 71G in the conductor pattern 71 is peeled off, and then the acrylic film The electromagnetic wave shielding layer 73 is formed by winding a copper foil (or aluminum foil or the like) with a conductive adhesive so as to cover the whole. In the FFC 700 having such a structure, the electromagnetic wave shielding layer 73 and the ground wire 71 are strongly connected so that the metal foil for blocking the noise is not removed due to stress such as bending or twisting of the cable itself. Need to be raised.

  The FPC 700 of FIG. 7 is a long flat flexible cable having a line pattern 71 (conductor pattern) at the center and a shield pattern 73 on the front side. The FPC 700 has a bent portion (not shown) at a position intersecting the wiring direction of the line pattern 71, and the bent portion has a bent line (not shown) perpendicular to the bent direction. Then, as the shield pattern 73 disposed on the surface of the FPC 700, if a wiring parallel to the fold line is provided in the bent portion, the shield pattern 73 can be formed as a shield structure similar to the shield pattern of FIG. 1 or FIG. Can do.

It is structural drawing and explanatory drawing which show the example which applied this invention to the flexible printed wiring board (FPC). It is a figure which shows another structure when this invention is applied to a flexible printed wiring board (FPC). It is a figure which shows the 1st example of the conventional shield structure in FPC. It is a figure which shows the 2nd example of the conventional shield structure in FPC. It is a figure which shows the 3rd example of the conventional shield structure in FPC. It is a figure which shows the structural example of FPC (flexible printed wiring board) to which this invention is applied. It is a figure which shows the structural example of FPC (flexible flat cable) to which this invention is applied.

Explanation of symbols

100, 200 FPC (flexible printed wiring board)
LP1 line pattern (wiring pattern)
SP1 Shield pattern (shield pattern)
A1 Main part A1 (Upper wiring part)
B1 Middle part (folded part)
C1 main part C1 (lower wiring part)
D1, D1 'Bending direction BS1 Bending line y1-y12 Horizontal wiring x1, x2 Vertical wiring P1, P2, P3 Shield pattern y22, y22 Horizontal wiring x21, x22 Vertical wiring 700 FPC (Flexible flat cable)
71 Line pattern (conductor layer)
73 Shield pattern (shield layer)

Claims (4)

In a long flat plate-shaped flexible wiring body in which a line pattern and a shield pattern are wired together,
The flexible wiring body has a bent portion at a position intersecting the wiring direction of the line pattern,
The folding portion has a folding line orthogonal to the folding direction;
The flexible wiring body, wherein the shield pattern includes a wiring parallel to the folding line at the bent portion. In the flexible wiring body according to claim 1,
The flexible wiring body, wherein the shield pattern includes a wiring parallel to the bending line and a wiring intersecting with the bending line in the bent portion. In the flexible wiring body according to claim 2,
The flexible wiring body, wherein the shield pattern is configured in a ladder pattern by a plurality of wirings parallel to the folding line and at least two wirings orthogonal to the folding line. In the flexible wiring body according to claim 1,
The shield pattern includes a wiring pattern in the bent portion, and a wiring pattern other than the bent portion,
The flexible wiring body, wherein the wiring pattern other than the bent portion is configured by a mesh pattern or a solid ground pattern.

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